The present invention relates to a film deposition method for forming a carbon thin film on a surface such as a plastic substrate.
Conventionally, functional thin films excellent in various physical properties such as a refractive index and conductivity, attracts attention as components of various devices. An example of these functional thin films is a carbon thin film with electric conductive properties which are improved by implanting nitrogen ions with an ion implantation. The carbon thin film has an advantage of being easily formed because existing ion implantation procedures can be utilized for forming the carbon thin film, but it has a disadvantage of difficulty in controlling physical properties of the carbon thin film for providing desired performances, due to reactivity of the carbon thin film to the nitrogen ions.
In recent years, functional thin films with more various physical properties and high quality are demanded to correspond to progresses of various devices. However, in conventional methods of forming the carbon thin film using the existing ion implantation, it is difficult to secure more various physical properties and to improve the quality of the carbon thin film due to the above disadvantages of controlling the physical properties, which are problems.
The present invention has been achieved in view of the above problems. It is an object of the invention to provide a film deposition method which allows a high-quality functional thin film, which is excellent in various physical properties, to be formed on a surface such as a plastic substrate.
A film deposition method of the invention is a method of forming a carbon thin film on a surface of a processing object, comprises a first step of generating first carbon ions and forming a carbon precursor film on the surface of the processing object with the first carbon ions, with no voltage applied to the processing object, and a second step of generating second carbon ions and implanting the second carbon ions in the carbon precursor film, with a pulsed voltage containing a negative pulse voltage applied to the processing object, wherein both of the first carbon ions and the second carbon ions are generated by evaporating a cathode containing carbon using energy of arc discharges.
According to the film deposition method of the invention, first, the carbon precursor film is formed on the surface of the processing object using the first carbon ions with no voltage applied to the processing object, in the first step. Then, in the second step, the second carbon ions are implanted in the carbon precursor film with the pulsed voltage containing the negative pulse voltage which is applied to the processing object. Both of the first carbon ions and the second carbon ions are generated by evaporating the cathode containing carbon with the energy of the arc discharges. Thereby, the high-quality carbon thin film having the various physical properties such as a refractive index, conductivity, and hardness is formed on the surface of the processing object.